Method of heating carbon articles.



No. 786,859. PATENTED APR. 11, 1905.

. V 15. J. TONE.

METHOD 0}? HEATING CARBON ARTICLES.

APPLICATION FILED APR. 2, 1904.

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UNITED STATES Patented April 11, 1905.

PATENT OFFICE.-

FRANK J. TONE, OF NIAGARA FALLS, NElV YORK.

SPECIFICATION forming part of Letters Patent No. 786,859, dated April 11, 1905.

Application filed April 2, 1904. Serial No. 201,317.

To all whmn it may concern.-

Be it known that I, FRANK J. ToNn, a citizen of the United States, residing at Niagara Falls, in the county of Niagara and State of New York, have invented certain new and useful Improvements in Methods of Heating Carbon Articles, of which the following is a specification.

This invention relates to the baking and heating of carbon articles-such as carbon brushes, batteryplates, and electrodes for furnaces and electrolytic bathsthe objects of the heating being to free the carbon from volatile matter, to improve its electrical conductivity, to increase its resistance to oxidation, and to impart to it other valuable properties.

The method consists, essentially, in placing the articles in proximity to but out of contact with a resistance-conductor, passing an electric current through said conductor, and heating the articles by radiation and convection therefrom. The articles are conveniently arranged in groups or masses without interposed insulation and are separated from the resistance conductor or core by a small space which is initially filled with air, but later wholly or in part by volatile and gaseous products of the operation, said space being sul'licient to preclude electrical contact between the articles and the conductor or core.

There are well-known methods of electrically heating carbon articles in which the current passes wholly or partly through the articles themselves and the material in which they are packed or bedded. It has been proposed to employ a separate core, around which the articles are grouped, the articles being separated from the core and from each other by interposed refractory material. In such case no effective insulation of the articles is possible at the working temperature of the furnace. I prefer to use a separate resistanceconductor or core, for the reason that such conductor or core can be restricted. in size and designed to offer such resistance that an excessive current will not be required. It can,

moreover, be built up in permanent form, so as not to require rebuilding or renewal after each run.

By the use of a space, as above described,

between the resistance-conductor and the articles to be baked or heated l substantially limit the current to said conductor.

The employment of a space for the purpose of insulating the mass of carbon articles from the core and confining the working current to the core has distinct advantages over other methods of insulation. Any solid insulating material must necessarily contain substances other than carbon, and the carbon articles are thus liable to contamination from the volatilization of the foreign substance and its absorption by, combination with, or adhesion to the articles. The space enables the carbon articles to be heated by convection and by radiation and a more uniform distribution of heat results.

By arranging the articles in proximity to the conductor but out of electrical contact therewith articles of various sizes and shapes can be disposed in any convenient manner or in a way conditioned solely by the require ments for proper baking or heating, it not being necessary in this case to so place them as to obtain certain relations of resistance and of current density.

For a fuller understanding of my invention reference is made to the accompanying drawings, wherein Figure 1 is a vertical section of one form of my furnace. Fig. 2 is a horizontal section thereof on the line 11 ll of Fig. 1, and Fig. 3 is a horizontal section of a modified construction.

Referring to the figures, 1 represents the resistance-conductor, here indicated as a core, which may conveniently be built up of plates or blocks of carbon, as indicated. Suitable terminals 2 2 are provided. The core rests upon a refractory base 3, and. the articles a to be heated are arranged in proximity to the core, but out of contact therewith, a space 5, which is initially filled-with air, being left between the core and the articles. Said space effectively insulates the articles from the core, but permits them to be uniformly heated by radiation and convection therefrom. Good results may be obtained with a space of one half to three fourths of an inch between the core and the articles. \Vhen in operation the air in the space 5 is displaced wholly or in part by carbon monoxid or other volatile or gaseous substances, the space does not cease to fulfil its function as an insulator. The carbon articles may be covered on the outside by a thin layer of powdered carbon 6 and may be further protected from oxidation by a suitable refractory material 7, such as a mixture of sand and powdered coke, which is heaped on top of the furnace. This material also prevents excessive radiation and loss of heat. Containing-walls of brick 8 constitute the sides and ends of the furnace.

The form of furnace shown in Fig. 3 comprises several conducting-cores arranged parallel to each other, the piles or groups of carbon articles being interposed between the cores and between the outer cores and the furnace-walls. This form of furnace is particularly useful in treating carbons of large size or considerable length and is, moreover, capable of being operated in a substantially continuous manner, the cores being successively connected with the source or sources of electric current, and the surrounding articles being thus successively treated. The heat radiated laterally from the mass of carbons is in such case not lost, but serves to heat the charge surrounding the core next to be connected. The result of such arrangement of cores and carbon articles and of said mode of operation is a considerable saving of energy. Instead of operating the cores successively, as described, they may be operated simultaneously either in series 01' in parallel from the source of current.

1 do not limit myself to the horizontal type of furnace, but may arrange the articles otherwise. For instance, the core may be a vertical column with the carbons piled around it and insulated by a space after the manner above described with reference to the horizontal furnace.

I claim 1. The herein-described method of heating carbon articles, which consists in placing the articles in proximity to, but out of contact with an electric resistance-conductor, the intermediate space serving as an insulator of electricity but a conductor of heat, and passing an electric current through the conductor, substantially as described.

2. The herein-described method of heating carbon articles, which consists in placing the articles in an electric furnace and in proximity to, but out of contact with an electric resistanee-conductor, the intermediate space serving as an insulator of electricity but a conductor of heat, and passing an electric current through the conductor, substantially as described.

3. The herein-described method of heating carbon articles, which consists in arranging the articles in piles in proximity to, but out of contact with an electric resistance-conductor, the intermediate space serving as an insulator of electricity but a conductor of heat, and passing an electric current through the conductor, substantially as described.

4:. The herein-described method of heating carbon articles, which consists in placing the articles in proximity to, but out of contact with a plurality of electric resistance-comluctors, the intermediate spaces serving as insulators of electricity but conductors of heat, and passing an electric current through the conductors, substantially as described.

5. The herein-described method of heating carbon articles, which consists in placing the articles in proximity to, but out of contact with a plurality of electric resistance-comlue tors, the intermediate spaces serving as insulators of electricity but conductors of heat, and passing electric current through the conductors in succession, substantially as described.

In testimony whereof I affix mysignature in presence of two witnesses.

FRANK J. TONE.

Vitnesses:

C. H. GREENWOOD, ASHMEAD G. Roncuns. 

